Corrosion resistant tubular article



Patented Oct. 18, 1938 UNITED STATES CORROSION RESISTANT TUBULAR ARTICLEDonald K. Crampton,

Marion, and Newell W.

Mitchell, Waterbury, Conn, assignors to Chase Brass & Copper (30.,Incorporated, Waterbury,

Conn., a corporation No Drawing. Application August 5, 1938,

Serial No. 223,272

Claims.

This invention relates to improvements in corrosion-resistant tubulararticles, and more particularly, corrosion-resistant wrought-metaltubular articles formed of copper-base alloys containing phosphorus,zinc and tin, with or without other elements which do not seriouslyimpair the properties of the alloy.

This application is a continuation-in-part of our application Serial No.71,807, filed March 30, 1936.

We have found that Wrought-metal tubular articles, such, for example, astubes, pipes, etc., made of copper-base alloys containing phosphorusfrom about to about 2%, zinc from about 1% to about 30%, tin from aboutto about 8%, and copper, the copper, phosphorus, zinc and tinconstituting about 90% or more of the alloy, with or without one or moreadditional elements in such substantially-innocuous amounts as do notseriously impair the properties of the alloy, have valuablecorrosion-resistant properties, especially when conveying or holding orotherwise contacting saline liquid or dilute acid. The additionalelements may range up to a total of about depending on what elements areadded, some being more innocuous than others.

While each of the elements iron and antimony should not be present muchin excess of about 0.1%, silver, which is comparatively innocuous, maybe present to as high as about 10% provided not too much of otherelements is present. Nickel may be present to as high as about 5 andlead and silicon may each be present to as high as about 3%.

We have discovered that aresnic has a particularly harmful eifect on thecorrosion resistance to saline liquid and dilute acid, of wroughtmetaltubular articles made of copper-base alloys herein set forth of copper,phosphorus, zinc and tin, even when the arsenic is present in very smallamount. We have discovered it to be important that the tubular articlesfor use in contact with saline liquid or dilute acid and formed of thesecopper-base alloys of copper, phosphorus, zinc and tin should besubstantially free from arsenic, that is, that arsenic, if present atall, should not be present in excess of 0.1%. We have found that arsenichas a very harmful action which brings about corrosion with consequentserious loss of tensile strength and ductility and ultimate destructionof the tubular article. Not only is this true when these articles aresubjected to plain corrosion without stress in the presence of salineliquid or dilute acid, but also when they are subjected to mechanicalstress in the presence of saline liquid or dilute acid. Under commercialconditions, the tubular articles are frequently used under mechanicalstress while subjected to corrosion by saline liquid or dilute acid, theamount or rate of corrosion being accelerated by the mechanical stress.Failure by stress corrosion in actual service is a very serious problem.We have discovered that wrought-metal tubular articles formed fromcopper-base alloys herein set forth of copper, phosphorus, zinc and tin,when substantially free of arsenic, have exceptional corrosionresistance to saline liquid and dilute acid, both when subjected tothese fluids under conditions of mechanical stress and free of stress.

Corrosion-resistant wrought-metal tubular articles in accordance withthis invention are preferably formed of copper-base alloys of copper,phosphorus, zinc and tin without additional elements, although aspreviously explained, certain additional elements may be toleratedprovided they are present only in such amounts as are substantiallyinnocuous.

Although the phosphorus may range from about to about 2%, the zinc fromabout 1% to 30%, and the tin from about to about 8%, it is preferable tohave the phosphorus from about to about 1 the zinc from about 3% toabout 20%, and the tin from about 1 to about 5%. Within the ranges ofthe elements of this preferred alloy range, three separate alloy typesmay advantageously be made, all having phosphorus from to about 1 /2%,the first having zinc from about 3%. to about 7% with the tin from about3% to about 5%, the second having zinc from about 7% to about 12% withthe tin from about 2% to about 4%, and a third having zinc from about12% to about 20% with the tin from about 1 to about 3%. And within theranges of said three alloy types, three alloys may be advantageouslymade having nominal composition as follows: all three have about 1%phosphorus, the first having about 5% zinc with about 4% tin, the secondhaving about 10% zinc with about 3% tin, and the third having about 15%zinc with about 2% tin.

In all the corrosion-resistant wrought-metal tubular articles made inaccordance with this invention, as the zinc content is increased fromabout 1% to about 30%, it is preferable to decrease both the ratioof tinto phosphorus and thecombined amounts of tin plus phosphorus.

The invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiment are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

We claim:

1. A wrought-metal tubular article for use in contact with saline liquidor dilute acid and characterized by good corrosion resistance to salineliquid and dilute acid and formed from an alloy substantially free ofarsenic and consisting of: phosphorus from about 4% to about 2%; zincfrom about 1% to about 30%; tin from about to about 8%; and the balancesubstantially of copper.

2. A wrought-metal tubular article for use in contact with saline liquidor dilute acid and characterized by good corrosion resistance to salineliqu d and dilute acid and formed from an alloy substantially free ofarsenic and consisting of: phosphorus from about A to about 1 zinc fromabout 3% to about 20%; tin from about 1 to about 5%; and the balancesubstantially of copper.

3. A Wrought-metal tubular article for use in contact with saline liquidor dilute acid and characterized by good corrosion resistance to salineliquid and dilute acid and formed from an alloy substantially free ofarsenic and consisting of: phosphorus from about J% to about 1 zinc fromabout 3% to about 1%; tin from about 3% to about 5%; and the balancesubstantially of copper.

4. A wrought-metal tubular article for use in contact with saline liquidor dilute acid and characterized by good corrosion resistance to salineliquid and dilute acid and formed from an alloy substantially free ofarsenic and consisting of: phosphorus from about to about 1 zinc fromabout 7% to about 12%; tin from about 2% to about 4%; and the balancesubstantially of copper.

5. A wrought-metal tubular article for use in contact with saline liquidor dilute acid and characterized by good corrosion resistance to salineliquid and dilute acid and formed from an alloy substantially free ofarsenic and consisting of: phosphorus from about to about 1 zinc fromabout 12% to about 20%; tin from about 1 5% to about 3%; and the balancesubstantially of copper.

DONALD K. CRAMPTON. N. W. MITCHELL.

